Israeli police investigators questioned Prime Minister Benjamin Netanyahu for three hours at his official residence on Monday evening on suspicion of receiving illicit gifts and favors from business executives.
Mr. Netanyahu was questioned “under caution,” the police said in a statement, implying that there were grounds to suspect that Mr. Netanyahu might have committed a criminal offense. “No further details can be given at this stage,” the statement added.
The Ministry of Justice said late Monday that Mr. Netanyahu had been questioned by investigators from Lahav 433, a police fraud investigation and prosecution unit, with the authorization of the attorney general, Avichai Mandelblit.
In a detailed statement, the ministry described how the police had gathered testimony from dozens of witnesses, some abroad, and seized documents during a monthslong graft inquiry. While some aspects of the inquiry did not yield evidence of crimes, the statement said, other parts warranted a deeper investigation.
Mr. Netanyahu, who has been subject to police inquiries and investigations in the past that ended without charges, has vehemently denied any impropriety. “This will all come to nothing, because there is nothing,” he has said repeatedly of the latest accusations.
Local news outlets say the investigators are focused on two separate cases, one more serious than the other, but they have offered little detail on the more serious one.
The less weighty one, according to reports in the newspaper Haaretz and other outlets, concerns favors for Mr. Netanyahu, and possibly for members of his family, given by Israeli and foreign business executives. The Israeli police took testimony from Ronald S. Lauder, a conservative American businessman and philanthropist, and a close friend of Mr. Netanyahu’s, when he came to Israel in late September to attend the funeral of Shimon Peres, the former prime minister and president.
Upon Mr. Lauder’s arrival in Israel, he was asked to meet with the Israeli police “and respond to questions related to an investigation, to which Mr. Lauder is not a party,” Helena Beilin, a Tel Aviv-based lawyer representing Mr. Lauder, said in a statement. “After a short meeting the following day, he was told that his presence was no longer needed and that there would be no need for additional meetings. This remains the case.”
Mr. Netanyahu’s office, suggesting that he is the victim of a witch hunt, issued a statement over the weekend berating the news organizations for what it described as premature and politically motivated reports. “Try to replace the prime minister at the ballot boxes, as is accepted in democracies,” it added.
In televised remarks on Monday afternoon, Mr. Netanyahu told legislators from his conservative Likud Party in Parliament, “We hear the celebratory spirit and winds blowing through the television studios and in the corridors of the opposition.”
“Hold off the celebrations; don’t rush,” he added. “I’ve told you before and will tell you again — this will come to nothing, because there is nothing.”
Mr. Netanyahu is serving his third consecutive term in office, and his fourth over all. He has exuded confidence lately, lashing out at journalists who have been critical of him, talking up Israel’s diplomatic and economic achievements, and calling in the United States ambassador to Israel, Daniel B. Shapiro, for a dressing down late last month after the Obama administration decided not to use its veto to shield Israel from a United Nations Security Council resolution that condemned Israeli settlement construction in the occupied West Bank and East Jerusalem.
Mr. Netanyahu, generally a popular prime minister, has developed a combative relationship with the local mainstream news media. After years of tension with the Obama administration, he also appears buoyed by the prospect of a partnership with President-elect Donald J. Trump, who seems more sympathetic to Israeli government policies on issues like settlements.
For Mr. Netanyahu’s opponents, the prospect of a possible indictment has provided a glimmer of hope, even though elections are not scheduled until late 2019.
“This creates an unusual dynamic in Israeli politics,” said Nahum Barnea, a political columnist for the newspaper Yedioth Ahronoth and a critic of Mr. Netanyahu. On the one hand, Mr. Barnea said, there were already signs that Netanyahu loyalists would try to promote legislation banning investigations of sitting prime ministers. On the other, he said, the question of who might succeed Mr. Netanyahu, who has no natural heir in his party, was bound to be raised.
Opposition leaders were fairly subdued in their initial response. Isaac Herzog, the leader of the Zionist Union and of the opposition in Parliament, said it was “a tough day for Israel when a prime minister is under investigation.”
He added, “We are not expressing satisfaction at another’s misfortune.” Mr. Herzog has also been the subject of police investigations over campaign funding.
Yair Lapid, the leader of the centrist Yesh Atid party, which has challenged Likud in recent polls, said, “The presumption of innocence applies to every Israeli, including the prime minister.” He called for a swift investigation for the sake of the country, saying, “A person who is being investigated is a person under pressure.”
Israeli prime ministers are not obligated to step down while under investigation, unless they are charged with a crime. Nonetheless, the accusations could chip away at Mr. Netanyahu’s standing. His predecessor, Ehud Olmert, was forced from power in 2008 under the weight of police investigations and accusations of corruption, although he remained in office as a caretaker prime minister until early elections could be held in 2009.
In February, Mr. Olmert became the first former Israeli prime minister to enter prison. He is serving a 19-month term for bribery and obstruction of justice.
Mr. Netanyahu described Mr. Olmert in 2008 as a “prime minister up to his neck in investigations” and said he could not be trusted to make fateful decisions under the circumstances because they might be based on personal rather than national interests.
Since the 1990s, Mr. Netanyahu’s political career has been dogged by inquiries into his conduct, and that of people around him, though no charges have been filed against him. The inquiries have ranged from scandals involving travel expenses and garden furniture — the Netanyahus were suspected of having switched a new set bought for the prime minister’s official residence with an identical, old set in their private home in Caesarea — to a more recent one involving a billion-dollar deal with Germany for the acquisition of submarines.
That agreement came under scrutiny after it became known that Mr. Netanyahu’s personal lawyer also represents the Israeli agent of the German shipyard that builds the submarines, and other naval equipment purchased by Israel, giving rise to suspicion of a conflict of interest.
In that episode, too, Mr. Netanyahu and the lawyer, David Shimron, have denied any wrongdoing.
Mr. Netanyahu’s relationship with Arnaud Mimran, a French tycoon who was convicted of fraud last year, and who testified that he had contributed a large sum of money to Mr. Netanyahu for his 2009 election campaign, has also prompted suspicions of impropriety.